That is correct.. I should have been more clear in my description.. This is actually more a snip for keeping a history of files instead of a history of logfiles... (I use it for rotating intermediate files used in NIS edited by many people using a 'special' script).
Aah, I see. Well, while I'm giving unbidden advice ;-), I've found that in situations such as you describe it is beneficial to use an SCM software such as subversion. This makes it easy for many people to collaborate without one accidentally overwriting someone else's changes and gives you a nice history of who changed what when. Also, channeling the update through a repository action gives you another hook to add custom behaviour. Just a thought.
A computer is a state machine. Threads are for people who can't program state machines. -- Alan Cox
Actually this script used to use RCS for locking/logging, but we found out it was giving more problems than benefits... So now we're changing it to something simpler (read: not depending too much on other software), including our own type of (more descriptive) locking... We now keep a couple of versions of the file, which makes restoring problems quicker in our environment.